Deciding between Canon 10-22, Sigma 8-16 / other UWA crop lenses

I currently have a T1i, the 18-55 IS kit lens and the 50mm f1.8. I'm going to europe in a couple of months (paris, barcelona, rome, etc) and based on previous visits there one thing I need is more width than the kit lens can provide. I've been reading a lot and have narrowed my choices to either the canon 10-22 or the sigma 8-16.
Can anyone recommend what lens they would purchase in my situation?

I'm currently leaning towards the canon because I don't think I'll need the 8-9 mm range and it would be useful to get close to a normal focal length if I want to take a snapshot of my friends.
On the other hand the sigma seems to have outstanding IQ ...